New sessions, kill consensus module (#2802)

* Draft of new sessions

* Reintroduce tuple impls

* Move staking module to new session API

* More work on staking and grandpa.

* Use iterator to avoid cloning and tuple macro

* Make runtime build again

* Polish the OpaqueKeys devex

* Move consensus logic into system & aura.

* Fix up system module

* Get build mostly going. Stuck at service.rs

* Building again

* Update srml/staking/src/lib.rs

Co-Authored-By: DemiMarie-parity <48690212+DemiMarie-parity@users.noreply.github.com>

* Refactoring out Consensus module, AuthorityIdOf, &c.

* Refactored out DigestItem::AuthoritiesChanged. Building.

* Remove tentative code

* Remove invalid comment

* Make Seal opaque and introduce nice methods for handling opaque items.

* Start to use proper digest for Aura authorities tracking.

* Fix up grandpa, remove system::Raw/Log

* Refactor Grandpa to use new logging infrastructure.

Also make authorityid/sessionkey static. Switch over to storing
authorities in a straight Vec.

* Building again

* Tidy up some AuthorityIds

* Expunge most of the rest of the AuthorityKey confusion.

Also, de-generify Babe and re-generify Aura.

* Remove cruft

* Untangle last of the `AuthorityId`s.

* Sort out finality_tracker

* Refactor median getting

* Apply suggestions from code review

Co-Authored-By: Robert Habermeier <rphmeier@gmail.com>

* Session tests works

* Update core/sr-primitives/src/generic/digest.rs

Co-Authored-By: DemiMarie-parity <48690212+DemiMarie-parity@users.noreply.github.com>

* Session tests works

* Fix for staking from @dvc94ch

* log an error

* fix test runtime build

* Some test fixes

* Staking mock update to new session api.

* Fix build.

* Move OpaqueKeys to primitives.

* Use on_initialize instead of check_rotate_session.

* Update tests to new staking api.

* fixup mock

* Fix bond_extra_and_withdraw_unbonded_works.

* Fix bond_with_little_staked_value_bounded_by_slot_stake.

* Fix bond_with_no_staked_value.

* Fix change_controller_works.

* Fix less_than_needed_candidates_works.

* Fix multi_era_reward_should_work.

* Fix nominating_and_rewards_should_work.

* Fix nominators_also_get_slashed.

* Fix phragmen_large_scale_test.

* Fix phragmen_poc_works.

* Fix phragmen_score_should_be_accurate_on_large_stakes.

* Fix phragmen_should_not_overflow.

* Fix reward_destination_works.

* Fix rewards_should_work.

* Fix sessions_and_eras_should_work.

* Fix slot_stake_is_least_staked_validator.

* Fix too_many_unbond_calls_should_not_work.

* Fix wrong_vote_is_null.

* Fix runtime.

* Fix wasm runtime build.

* Update Cargo.lock

* Fix warnings.

* Fix grandpa tests.

* Fix test-runtime build.

* Fix template node build.

* Fix stuff.

* Update Cargo.lock to fix CI

* Re-add missing AuRa logs

Runtimes are required to know about every digest they receive ― they
panic otherwise.  This re-adds support for AuRa pre-runtime digests.

* Update core/consensus/babe/src/digest.rs

Co-Authored-By: DemiMarie-parity <48690212+DemiMarie-parity@users.noreply.github.com>

* Kill log trait and all that jazz.

* Refactor staking tests.

* Fix ci runtime wasm check.

* Line length 120.

* Make tests build again

* Remove trailing commas in function declarations

The `extern_functions!` macro doesn’t like them, perhaps due to a bug in
rustc.

* Fix type error

* Fix compilation errors

* Fix a test

* Another couple of fixes

* Fix another test

* More test fixes

* Another test fix

* Bump runtime.

* Wrap long line

* Fix build, remove redundant code.

* Issue to track TODO

* Leave the benchmark code alone.

* Fix missing `std::time::{Instant, Duration}`

* Indentation

* Aura ConsensusLog as enum

substrate/core/consensus/babe/primitives/Cargo.toml

@@ -7,13 +7,16 @@ edition = "2018"
 
 [dependencies]
 substrate-client = { path = "../../../client", default-features = false }
+rstd = { package = "sr-std", path = "../../../sr-std", default-features = false }
 runtime_primitives = { package = "sr-primitives", path = "../../../sr-primitives", default-features = false }
+substrate-primitives = { path = "../../../primitives", default-features = false }
 slots = { package = "substrate-consensus-slots", path = "../../slots", optional = true }
 parity-codec = { version = "3.5.1", default-features = false }
 
 [features]
 default = ["std"]
 std = [
+	"rstd/std",
 	"runtime_primitives/std",
 	"substrate-client/std",
 	"parity-codec/std",

substrate/core/consensus/babe/primitives/src/lib.rs

@@ -18,13 +18,18 @@
 #![deny(warnings, unsafe_code, missing_docs)]
 #![cfg_attr(not(feature = "std"), no_std)]
 
+use parity_codec::{Encode, Decode};
+use rstd::vec::Vec;
 use runtime_primitives::ConsensusEngineId;
+use substrate_primitives::sr25519::Public;
 use substrate_client::decl_runtime_apis;
 
-use parity_codec::{Encode, Decode};
+/// A Babe authority identifier. Necessarily equivalent to the schnorrkel public key used in
+/// the main Babe module. If that ever changes, then this must, too.
+pub type AuthorityId = Public;
 
 /// The `ConsensusEngineId` of BABE.
-pub const BABE_ENGINE_ID: ConsensusEngineId = [b'b', b'a', b'b', b'e'];
+pub const BABE_ENGINE_ID: ConsensusEngineId = *b"BABE";
 
 /// Configuration data used by the BABE consensus engine.
 #[derive(Copy, Clone, Hash, PartialEq, Eq, Debug, Encode, Decode)]
@@ -69,5 +74,8 @@ decl_runtime_apis! {
 		///
 		/// Dynamic configuration may be supported in the future.
 		fn startup_data() -> BabeConfiguration;
+
+		/// Get the current authorites for Babe.
+		fn authorities() -> Vec<AuthorityId>;
 	}
 }